Alcubierre drive

   

The Alcubierre drive, also known as the Warp drive, is a hypothetical method for propelling a spacecraft faster than the speed of light.

Diagram of an Alcubierre warp field

Ordinary matter distorts the geometry of spacetime, causing the effects of gravity. The physicist Miguel Alcubierre proposed a method of stretching space in a wave, causing the space "ahead" of a spacecraft to contract along the axis the spacecraft wishes to travel in and the space "behind" it to expand. The ship would ride this wave inside a region of flat space. Since the ship is not actually moving within this region, but rather being carried along as the region itself moves, conventional relativistic effects do not apply. There is no way known to induce such a wave, however, or to leave it once started; the Alcubierre drive remains a theoretical concept at this time.

For those familiar with usual rules of special relativity, with its Lorentz contraction, mass increase, and time dilation, the Alcubierre warp metric has some rather peculiar aspects. Since a ship at the center of the moving volume of the metric is at rest with respect to locally flat space, there are no relativistic mass increase or time dilation effects. The on-board spaceship clock runs at the same speed as the clock of an external observer, and that observer will detect no increase in the mass of the moving ship, even when it travels at FTL speeds. Moreover, Alcubierre has shown that even when the ship is accelerating, it travels on a free-fall geodesic. In other words, a ship using the warp to accelerate and decelerate is always in free fall, and the crew would experience no accelerational g-forces. Enormous tidal forces would be present near the edges of the flat-space volume because of the large space curvature there, but by suitable specification of the metric, these would be made very small within the volume occupied by the ship.

Note that the term "Warp drive" is used in science fiction to denote a wide variety of imaginary propulsion methods, most of which have nothing to do with the Alcubierre drive or any other physical theory.

See also

Reference

  • The Giant Leap: Mankind Heads for the Stars by Adrian Berry (ISBN 0312877854)

External link


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